1. Technical Field
The present invention relates to improvements in network design and in particular to improved methods and systems for simultaneous capacity calculation in a shared transmission medium network. Still more particularly, the present invention relates to a method and system for simultaneous capacity calculation for multimedia services under aggregate traffic conditions which can be utilized in systems having both central queues and distributed queues.
2. Description of the Related Art
No where has the explosion of modern technology been more evident than in the field of communication. The number and type of communication services has been rapidly expanding, including so-called "multimedia" services such as video teleconferencing, video/movies on demand and the like.
The intermixing of these multimedia services with traditional data and voice communications within a shared transmission medium has presented various design problems. For example, consider a system which receives packetized telecommunication traffic from n multimedia services which are queued either in one central queue or in multiple distributed queues wherein one queue is associated with each service. Thus, if more than n subscribers to the services are utilizing the network at any given time, the received packets which are not processed by the system are queued. During heavy use periods, as the number of users increase, and these queues become quite large, certain packets may be discarded based upon a priority scheme, delay will increase, and quality of service will suffer.
Consequently, those skilled in the art will appreciate that one design requirement for a viable multimedia network requires that a limit exits for the number of users simultaneously connected to the network so that customer expectations, quality of service parameters, and network efficiency will not suffer.
One common technique utilized in the past to satisfy customer expectations is to ensure that the quality of service parameter values for the multimedia services are not exceeded. In view of the fact that a modern network may include multiple diverse multimedia services having variable quality of service values, it should be apparent that it would be advantageous to have a technique which could be utilized to calculate simultaneous capacity in an efficient and accurate manner.
In the past, attempts at statistically modeling aggregate traffic which originates from homogenous services with similar traffic types and similar characteristics have been proposed. For example, the Poisson Process is widely utilized to model aggregate traffic from voice sources. Similarly, the discreet Auto Regressive Process has been utilized to model aggregate traffic from video-teleconferencing sources. A Markov Modulated Poisson Process is often utilized to model aggregate traffic from data sources. These techniques typically require complex mathematical expressions which are not explicit and which require time-consuming numerical methods to solve.
Further, these expressions do not apply directly to the problem of networks having diverse multimedia services with different quality of service values. For example, utilizing the known expressions in the prior art with the most stringent quality of service values for the various services within the network will result in a gross under-estimate of the simultaneous capacity of the network and therefore a loss of potential revenue to system operators. Similarly, applying the expressions for the most lenient quality of service values results in a gross over-estimate of simultaneous capacity and therefore a violation of the quality of service values during heavy traffic load situations.
Thus, those skilled in the art will appreciate that a method and system for accurately and efficiently calculating simultaneous capacity of multimedia services under aggregate traffic conditions would greatly enhance the efficiency of network design and the level of customer satisfaction.